[_dain_]

Nobody said it had to be Common Lisp. I'm going by the notation the grandparent commenter used. My point was that indentation can clarify the structure of nested sexps vs putting them on one line. And that is actually what people do. "mod" vs "%" hasn't the least to do with it. This isn't even really about arithmetic; those are just at-hand examples the GP commenter chose. Could just as well have been

  (foo 
    (bar
      (baz (bax x 2)
           "hello")
      "world")
    "!")

>the brackets you and the parent used in the s-expr are around the wrong groups of symbols

No they're not. Yours is wrong. Multiplication has higher priority than addition so the order of evaluation begins with (x * 2) not (1 + x).

[andsoitis]

> No they're not. Yours is wrong. Multiplication has higher priority than addition so the order of evaluation begins with (x * 2) not (1 + x).

OK, I shouldn't have gone that far.

FWIW, modulus has the same operator precedence as multiplication and division.

So really, it is more like:

(- (+ 1 (* x 2))

   (mod 3 x))

or using the increment function:

(- (1+ (* x 2))

   (mod 3 x))

[_dain_]

Alright well I guess this is an object lesson in why infix notation is bad -- nobody can remember all the precedence rules once you get beyond +-*/^.

[andsoitis]

We'll call it even :-)